From patchwork Thu Sep 1 07:12:35 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Florian Westphal X-Patchwork-Id: 12961900 X-Patchwork-Delegate: kuba@kernel.org Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id D93AFC64991 for ; Thu, 1 Sep 2022 07:13:21 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233705AbiIAHNU (ORCPT ); Thu, 1 Sep 2022 03:13:20 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:48170 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233604AbiIAHM7 (ORCPT ); Thu, 1 Sep 2022 03:12:59 -0400 Received: from Chamillionaire.breakpoint.cc (Chamillionaire.breakpoint.cc [IPv6:2a0a:51c0:0:12e:520::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 61881E1936; Thu, 1 Sep 2022 00:12:57 -0700 (PDT) Received: from fw by Chamillionaire.breakpoint.cc with local (Exim 4.92) (envelope-from ) id 1oTeNj-0000XB-T1; Thu, 01 Sep 2022 09:12:55 +0200 From: Florian Westphal To: Cc: davem@davemloft.net, netfilter-devel@vger.kernel.org, kuba@kernel.org, pabeni@redhat.com, edumazet@google.com, Pablo Neira Ayuso , Aaron Conole Subject: [PATCH net 1/4] netfilter: remove nf_conntrack_helper sysctl and modparam toggles Date: Thu, 1 Sep 2022 09:12:35 +0200 Message-Id: <20220901071238.3044-2-fw@strlen.de> X-Mailer: git-send-email 2.35.1 In-Reply-To: <20220901071238.3044-1-fw@strlen.de> References: <20220901071238.3044-1-fw@strlen.de> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org X-Patchwork-Delegate: kuba@kernel.org From: Pablo Neira Ayuso __nf_ct_try_assign_helper() remains in place but it now requires a template to configure the helper. A toggle to disable automatic helper assignment was added by: a9006892643a ("netfilter: nf_ct_helper: allow to disable automatic helper assignment") in 2012 to address the issues described in "Secure use of iptables and connection tracking helpers". Automatic conntrack helper assignment was disabled by: 3bb398d925ec ("netfilter: nf_ct_helper: disable automatic helper assignment") back in 2016. This patch removes the sysctl and modparam toggles, users now have to rely on explicit conntrack helper configuration via ruleset. Update tools/testing/selftests/netfilter/nft_conntrack_helper.sh to check that auto-assignment does not happen anymore. Acked-by: Aaron Conole Signed-off-by: Pablo Neira Ayuso --- include/net/netfilter/nf_conntrack.h | 2 - include/net/netns/conntrack.h | 1 - net/netfilter/nf_conntrack_core.c | 7 +- net/netfilter/nf_conntrack_helper.c | 80 +++---------------- net/netfilter/nf_conntrack_netlink.c | 5 -- net/netfilter/nf_conntrack_standalone.c | 10 --- net/netfilter/nft_ct.c | 3 - .../netfilter/nft_conntrack_helper.sh | 36 ++++++--- 8 files changed, 37 insertions(+), 107 deletions(-) diff --git a/include/net/netfilter/nf_conntrack.h b/include/net/netfilter/nf_conntrack.h index a32be8aa7ed2..6a2019aaa464 100644 --- a/include/net/netfilter/nf_conntrack.h +++ b/include/net/netfilter/nf_conntrack.h @@ -53,8 +53,6 @@ struct nf_conntrack_net { /* only used when new connection is allocated: */ atomic_t count; unsigned int expect_count; - u8 sysctl_auto_assign_helper; - bool auto_assign_helper_warned; /* only used from work queues, configuration plane, and so on: */ unsigned int users4; diff --git a/include/net/netns/conntrack.h b/include/net/netns/conntrack.h index c396a3862e80..e1290c159184 100644 --- a/include/net/netns/conntrack.h +++ b/include/net/netns/conntrack.h @@ -101,7 +101,6 @@ struct netns_ct { u8 sysctl_log_invalid; /* Log invalid packets */ u8 sysctl_events; u8 sysctl_acct; - u8 sysctl_auto_assign_helper; u8 sysctl_tstamp; u8 sysctl_checksum; diff --git a/net/netfilter/nf_conntrack_core.c b/net/netfilter/nf_conntrack_core.c index 71c2f4f95d36..1357a2729a4b 100644 --- a/net/netfilter/nf_conntrack_core.c +++ b/net/netfilter/nf_conntrack_core.c @@ -1782,7 +1782,7 @@ init_conntrack(struct net *net, struct nf_conn *tmpl, } spin_unlock_bh(&nf_conntrack_expect_lock); } - if (!exp) + if (!exp && tmpl) __nf_ct_try_assign_helper(ct, tmpl, GFP_ATOMIC); /* Other CPU might have obtained a pointer to this object before it was @@ -2068,10 +2068,6 @@ void nf_conntrack_alter_reply(struct nf_conn *ct, ct->tuplehash[IP_CT_DIR_REPLY].tuple = *newreply; if (ct->master || (help && !hlist_empty(&help->expectations))) return; - - rcu_read_lock(); - __nf_ct_try_assign_helper(ct, NULL, GFP_ATOMIC); - rcu_read_unlock(); } EXPORT_SYMBOL_GPL(nf_conntrack_alter_reply); @@ -2797,7 +2793,6 @@ int nf_conntrack_init_net(struct net *net) nf_conntrack_acct_pernet_init(net); nf_conntrack_tstamp_pernet_init(net); nf_conntrack_ecache_pernet_init(net); - nf_conntrack_helper_pernet_init(net); nf_conntrack_proto_pernet_init(net); return 0; diff --git a/net/netfilter/nf_conntrack_helper.c b/net/netfilter/nf_conntrack_helper.c index e96b32221444..ff737a76052e 100644 --- a/net/netfilter/nf_conntrack_helper.c +++ b/net/netfilter/nf_conntrack_helper.c @@ -35,11 +35,6 @@ unsigned int nf_ct_helper_hsize __read_mostly; EXPORT_SYMBOL_GPL(nf_ct_helper_hsize); static unsigned int nf_ct_helper_count __read_mostly; -static bool nf_ct_auto_assign_helper __read_mostly = false; -module_param_named(nf_conntrack_helper, nf_ct_auto_assign_helper, bool, 0644); -MODULE_PARM_DESC(nf_conntrack_helper, - "Enable automatic conntrack helper assignment (default 0)"); - static DEFINE_MUTEX(nf_ct_nat_helpers_mutex); static struct list_head nf_ct_nat_helpers __read_mostly; @@ -51,24 +46,6 @@ static unsigned int helper_hash(const struct nf_conntrack_tuple *tuple) (__force __u16)tuple->src.u.all) % nf_ct_helper_hsize; } -static struct nf_conntrack_helper * -__nf_ct_helper_find(const struct nf_conntrack_tuple *tuple) -{ - struct nf_conntrack_helper *helper; - struct nf_conntrack_tuple_mask mask = { .src.u.all = htons(0xFFFF) }; - unsigned int h; - - if (!nf_ct_helper_count) - return NULL; - - h = helper_hash(tuple); - hlist_for_each_entry_rcu(helper, &nf_ct_helper_hash[h], hnode) { - if (nf_ct_tuple_src_mask_cmp(tuple, &helper->tuple, &mask)) - return helper; - } - return NULL; -} - struct nf_conntrack_helper * __nf_conntrack_helper_find(const char *name, u16 l3num, u8 protonum) { @@ -209,33 +186,11 @@ nf_ct_helper_ext_add(struct nf_conn *ct, gfp_t gfp) } EXPORT_SYMBOL_GPL(nf_ct_helper_ext_add); -static struct nf_conntrack_helper * -nf_ct_lookup_helper(struct nf_conn *ct, struct net *net) -{ - struct nf_conntrack_net *cnet = nf_ct_pernet(net); - - if (!cnet->sysctl_auto_assign_helper) { - if (cnet->auto_assign_helper_warned) - return NULL; - if (!__nf_ct_helper_find(&ct->tuplehash[IP_CT_DIR_REPLY].tuple)) - return NULL; - pr_info("nf_conntrack: default automatic helper assignment " - "has been turned off for security reasons and CT-based " - "firewall rule not found. Use the iptables CT target " - "to attach helpers instead.\n"); - cnet->auto_assign_helper_warned = true; - return NULL; - } - - return __nf_ct_helper_find(&ct->tuplehash[IP_CT_DIR_REPLY].tuple); -} - int __nf_ct_try_assign_helper(struct nf_conn *ct, struct nf_conn *tmpl, gfp_t flags) { struct nf_conntrack_helper *helper = NULL; struct nf_conn_help *help; - struct net *net = nf_ct_net(ct); /* We already got a helper explicitly attached. The function * nf_conntrack_alter_reply - in case NAT is in use - asks for looking @@ -246,23 +201,21 @@ int __nf_ct_try_assign_helper(struct nf_conn *ct, struct nf_conn *tmpl, if (test_bit(IPS_HELPER_BIT, &ct->status)) return 0; - if (tmpl != NULL) { - help = nfct_help(tmpl); - if (help != NULL) { - helper = rcu_dereference(help->helper); - set_bit(IPS_HELPER_BIT, &ct->status); - } + if (WARN_ON_ONCE(!tmpl)) + return 0; + + help = nfct_help(tmpl); + if (help != NULL) { + helper = rcu_dereference(help->helper); + set_bit(IPS_HELPER_BIT, &ct->status); } help = nfct_help(ct); if (helper == NULL) { - helper = nf_ct_lookup_helper(ct, net); - if (helper == NULL) { - if (help) - RCU_INIT_POINTER(help->helper, NULL); - return 0; - } + if (help) + RCU_INIT_POINTER(help->helper, NULL); + return 0; } if (help == NULL) { @@ -545,19 +498,6 @@ void nf_nat_helper_unregister(struct nf_conntrack_nat_helper *nat) } EXPORT_SYMBOL_GPL(nf_nat_helper_unregister); -void nf_ct_set_auto_assign_helper_warned(struct net *net) -{ - nf_ct_pernet(net)->auto_assign_helper_warned = true; -} -EXPORT_SYMBOL_GPL(nf_ct_set_auto_assign_helper_warned); - -void nf_conntrack_helper_pernet_init(struct net *net) -{ - struct nf_conntrack_net *cnet = nf_ct_pernet(net); - - cnet->sysctl_auto_assign_helper = nf_ct_auto_assign_helper; -} - int nf_conntrack_helper_init(void) { nf_ct_helper_hsize = 1; /* gets rounded up to use one page */ diff --git a/net/netfilter/nf_conntrack_netlink.c b/net/netfilter/nf_conntrack_netlink.c index 04169b54f2a2..7562b215b932 100644 --- a/net/netfilter/nf_conntrack_netlink.c +++ b/net/netfilter/nf_conntrack_netlink.c @@ -2298,11 +2298,6 @@ ctnetlink_create_conntrack(struct net *net, ct->status |= IPS_HELPER; RCU_INIT_POINTER(help->helper, helper); } - } else { - /* try an implicit helper assignation */ - err = __nf_ct_try_assign_helper(ct, NULL, GFP_ATOMIC); - if (err < 0) - goto err2; } err = ctnetlink_setup_nat(ct, cda); diff --git a/net/netfilter/nf_conntrack_standalone.c b/net/netfilter/nf_conntrack_standalone.c index 05895878610c..4ffe84c5a82c 100644 --- a/net/netfilter/nf_conntrack_standalone.c +++ b/net/netfilter/nf_conntrack_standalone.c @@ -561,7 +561,6 @@ enum nf_ct_sysctl_index { NF_SYSCTL_CT_LOG_INVALID, NF_SYSCTL_CT_EXPECT_MAX, NF_SYSCTL_CT_ACCT, - NF_SYSCTL_CT_HELPER, #ifdef CONFIG_NF_CONNTRACK_EVENTS NF_SYSCTL_CT_EVENTS, #endif @@ -680,14 +679,6 @@ static struct ctl_table nf_ct_sysctl_table[] = { .extra1 = SYSCTL_ZERO, .extra2 = SYSCTL_ONE, }, - [NF_SYSCTL_CT_HELPER] = { - .procname = "nf_conntrack_helper", - .maxlen = sizeof(u8), - .mode = 0644, - .proc_handler = proc_dou8vec_minmax, - .extra1 = SYSCTL_ZERO, - .extra2 = SYSCTL_ONE, - }, #ifdef CONFIG_NF_CONNTRACK_EVENTS [NF_SYSCTL_CT_EVENTS] = { .procname = "nf_conntrack_events", @@ -1100,7 +1091,6 @@ static int nf_conntrack_standalone_init_sysctl(struct net *net) table[NF_SYSCTL_CT_CHECKSUM].data = &net->ct.sysctl_checksum; table[NF_SYSCTL_CT_LOG_INVALID].data = &net->ct.sysctl_log_invalid; table[NF_SYSCTL_CT_ACCT].data = &net->ct.sysctl_acct; - table[NF_SYSCTL_CT_HELPER].data = &cnet->sysctl_auto_assign_helper; #ifdef CONFIG_NF_CONNTRACK_EVENTS table[NF_SYSCTL_CT_EVENTS].data = &net->ct.sysctl_events; #endif diff --git a/net/netfilter/nft_ct.c b/net/netfilter/nft_ct.c index b04995c3e17f..a3f01f209a53 100644 --- a/net/netfilter/nft_ct.c +++ b/net/netfilter/nft_ct.c @@ -1089,9 +1089,6 @@ static int nft_ct_helper_obj_init(const struct nft_ctx *ctx, if (err < 0) goto err_put_helper; - /* Avoid the bogus warning, helper will be assigned after CT init */ - nf_ct_set_auto_assign_helper_warned(ctx->net); - return 0; err_put_helper: diff --git a/tools/testing/selftests/netfilter/nft_conntrack_helper.sh b/tools/testing/selftests/netfilter/nft_conntrack_helper.sh index bf6b9626c7dd..faa7778d7bd1 100755 --- a/tools/testing/selftests/netfilter/nft_conntrack_helper.sh +++ b/tools/testing/selftests/netfilter/nft_conntrack_helper.sh @@ -102,26 +102,42 @@ check_for_helper() ip netns exec ${netns} conntrack -L -f $family -p tcp --dport $port 2> /dev/null |grep -q 'helper=ftp' if [ $? -ne 0 ] ; then - echo "FAIL: ${netns} did not show attached helper $message" 1>&2 - ret=1 + if [ $autoassign -eq 0 ] ;then + echo "FAIL: ${netns} did not show attached helper $message" 1>&2 + ret=1 + else + echo "PASS: ${netns} did not show attached helper $message" 1>&2 + fi + else + if [ $autoassign -eq 0 ] ;then + echo "PASS: ${netns} connection on port $port has ftp helper attached" 1>&2 + else + echo "FAIL: ${netns} connection on port $port has ftp helper attached" 1>&2 + ret=1 + fi fi - echo "PASS: ${netns} connection on port $port has ftp helper attached" 1>&2 return 0 } test_helper() { local port=$1 - local msg=$2 + local autoassign=$2 + + if [ $autoassign -eq 0 ] ;then + msg="set via ruleset" + else + msg="auto-assign" + fi sleep 3 | ip netns exec ${ns2} nc -w 2 -l -p $port > /dev/null & sleep 1 | ip netns exec ${ns1} nc -w 2 10.0.1.2 $port > /dev/null & sleep 1 - check_for_helper "$ns1" "ip $msg" $port - check_for_helper "$ns2" "ip $msg" $port + check_for_helper "$ns1" "ip $msg" $port $autoassign + check_for_helper "$ns2" "ip $msg" $port $autoassign wait @@ -173,9 +189,9 @@ if [ $? -ne 0 ];then fi fi -test_helper 2121 "set via ruleset" -ip netns exec ${ns1} sysctl -q 'net.netfilter.nf_conntrack_helper=1' -ip netns exec ${ns2} sysctl -q 'net.netfilter.nf_conntrack_helper=1' -test_helper 21 "auto-assign" +test_helper 2121 0 +ip netns exec ${ns1} sysctl -qe 'net.netfilter.nf_conntrack_helper=1' +ip netns exec ${ns2} sysctl -qe 'net.netfilter.nf_conntrack_helper=1' +test_helper 21 1 exit $ret